Tool positioning device for machining the edges of sheet or plate materials

A device for angularly positioning a tool head for machining the edges of sheet or plate workpiece materials, wherein the machine comprises supporting means for rotatably supporting the tool head about a first axis in use extending tranverse to the plane of the workpiece, said supporting means including a shaft coaxial with said first axis and a bracket journalled with one end thereof on said shaft and carrying said tool head with the other end thereof offset thereto, said one end having a gear coaxial with said first axis, a D.C. motor having a pinion in mesh with said gear for controllably imparting angular movements to said tool head about said first axis and wherein said device comprises a freely swivelling tracer member having its own axis of rotation in use extending transverse to the plane of said workpiece and about which said swivelling tracer member is adapted to freely swivel, said tracer member having two spaced apart tracer point rollers movably engaging simultaneously in use the edge of the workpiece to be machined, said rollers being arranged in fixed position on said tracer member thereby to cause in use angular swivelling of said tracer member bodily therewith depending on the curvature profile of the edge of said workpiece against which said rollers engage, the device further comprising a rod extending transverse to said first axis and responsive to the angular displacement of said tracer member, said rod having a fork-like free end and a transducer arranged at least in part between the prongs of said fork-like end for controlling said D.C. motor for imparting controllable angular displacement to said tool head depending on the curvature profile against which said two rollers engage.